Part 8 – To obtain long-term success with AQB
Verification of a surgical procedure that is safe, secure, reliable, and thatmaximizes the properties of AQB

The conference was held at headquarter of Advance Co., Ltd. on June 4, 2009
AQB implants are known for its excellent characteristics, but the ways in which diagnosis, operation andmanagement should be conducted need to be clarified to achieve long-term stability. The four of theauthors who contributed long clinical case studies to this book participated in the debate to define theseissues to when gathered to mark the publication of this clinical edition.
Dr Tsutsumi, who has been involved with AQB since its developmental stages, acted as the Chairman forthis debate.

■Attendances of clinical case conference
Dr. Takao Kinebuchi(Director of Kinebuchi Dental Clinic)

Dr. Yushiro Kuroyama (Director of Kuroyama Oral and Maxillofacial Surgery Clinic)
Dr. Toshiaki Miyazawa (Director of Tokyo Kagawa Dental Clinic)
Dr. Yasuhiko Tsuyama (General Manager of Department of Dentistry, Oral andMaxillofacial Surgery, Mitsui Memorial Hospital)(Chairman)

Dr. Yoshichika Tsutsumi(Director of Medical Clinic at the Ministryof Foreign Affairs Division of Health and Welfare)Dr. Takao Kinebuchi

Dr. Yushirou Kuroyama•GraduatedGraduatedfrom
fromDepartmentof Dentistry,
Departmentof Dentistry,
TokyoTokyo
Medicaland Dental
DentalUniversity
University(TMDU),(TMDU),Doctor
DoctorMedical andof ofMedicalDentistry.
Medical Dentistry.
•Former
Formerpositions
positions
includeDirectorof Department
includeDirectorof DepartmentofofDentistry,
Oral
Maxillofacial
Surgery,
Mitsui
Dentistry,Oral
andandMaxillofacial
Surgery,
Mitsui
Memorial
Hospitalandcurrent
position.
Memorial Hospital and current position.
•Currently
CurrentlyHolds
Holds
the
post
a partinstructor
thepostof aofparttimetime
instructor
at
at
TMDU.
Specialistof JapaneseSocietyof OralTMDU.
Specialistof JapaneseSocietyof OralandandMaxillofacial
Surgeons
Maxillofacial Surgeons・ Graduated from Department of Dentistry, The
Nippon Dental University
・ Graduated from a doctorial course in Graduate
School of Medical and Dental Sciences, Tokyo
Medical and Dental University, Doctor of Medical
Dentistry.
・ Former positions include research fellowship(Doctor) of Japan Society for the Promotion of
Science and current position

Dr. Toshiaki Miyazawa

Dr. Yasuhiko Tsuyama

・Graduated from Department of Dentistry, Nippon
University.
・Former positions include director of Department of
Dentistry, Oral and Maxillofacial Surgery, Mitsui
Memorial Hospital and current position

・Graduated from Department of Dentistry, Kyusyu
University.
・ Former positions include an assistant at
Department of Oral and Maxillofacial Surgery,
Faculty of Medicine, The University of Tokyo and alecture at Department of Plastic Surgery, Kinki
University and current position
・Medical Advisor of Japanese Society of Oral andMaxillofacial Surgeons

The details of AQB development
Its launch in the midst of adverse conditions, backed by its outstanding properties
Tsutsumi: I would like to begin with the history of AQB implant development (Table 1) in before looking
at the case studies.
The development of AQB implants began at the Institute of medical and dental engineering, Tokyo
Medical and Dental University (TMDU), and ADVANCE Co., Ltd. in 1983.
The dental implants at that time included a string of failures: the blade type; periosteal implants;
followed by the introduction of hydroxyapatite (HA) sintered body, Apaceram by the domestic
manufacturer that had problems with its mechanical strength. The excellent osteoinduction of apatite
was already known at the time therefore we instigated the research and development of the apatitecomposite material that excelled in strength and osteoinducing abilities. I, at the time a member of theinstitute of medical devices, became involved in the development, and so did Dr Kutoyama, who wasenrolled at the Graduate School of Tokyo Medical and Dental University.
Kuroyama: I remember we were faced with the issue of coating titanium with highly crystalline HA at thedevelopmental stages. Initially, HA was spray coated onto the titanium as the raw material, but thismethod resulted in the inclusion of chemical compounds other than HA (i.e. impurities) such as
tetracalcium phosphate (TeCP) and calcium oxide (CaO). The impurities cause solubilization of thecoating layer. Eventually, the method of using β-TCP as the raw material, to primarily produce α-TCP
coating layer to be converted into recrystallized HA with hydrothermal treatment was derived, after trial
and error. I can remember the great efforts put into finding this by the members of ADVACE Co., Ltd.
Tsutsumi: The result of this effort is reflected in the idea of “recrystallization” of HA currently applied in
AQB. The issues of the presence of impurities were solved, giving rise to patented recrystallized HA
coated AQB with a crystallinity that is close to 97%.
Dr Kunebuchi and Dr Miyazawa, while you were working in Mitsui Memorial Hospital, the facility
chosen for the clinical trials, what were your impressions of AQB.
Kinebuchi: The surface structure of the AQB HA coating observed under the scanning electron microscope(SEM) was hugely different from other HA implants, it could be described as an „alive apatite‟ (Fig. 1).
Fig. 1 Electron micrograph of AQB recrystallized HA
The difference from those HA that are solubilized and lost their functions were extremely obvious in the
SEM image, and I did think this could have the potential and was expectant of the properties that the
AQB would show in the clinical settings.

Recrystallizedhydroxyapatite

Fig. 1 Electron micrograph of AQB recrystallized HAMiyazawa: I was using implants manufactured by other companies dominated by two-piece type at thetime. The fixture and abutment, abutment and superstructure were both fixed with screws, andremember being extremely wearily of its strength and the problems of screw loosening.
Tsutsumi: The secondary trials were started in November 1990 in Mitsui Memorial Hospital and The
Nippon Dental University, simultaneously. Thirty clinical examples were collected from the start to thefollowing November and submitted to the Ministry of Welfare (currently the Ministry of Health, Labourand Welfare) (Fig. 2), and was approved. The results were so astonishing that even the officer called us to
ask whether the figures were real.
As the evaluation criteria, we adopted the “Effective ratio” established by the Harvard Conference. This
standard is known for its strictness, even in comparison to the current survival rate criteria, in that evena minute movement would prevent the implant from being qualified. The AQB scored easily over 90%
success rate even with qualification method.
The first workshop was held in August the same year, in which Dr Kuroyama also participated, and thisbecame the start of the AQB action to be in full swing.
Tsuyama: Roughly a dozen or so members took part in the first workshop, and I remember seeing thesimplicity of the surgical techniques was like a breath of fresh air.

Fig. 2 Clinical trial documents of AQB

The long-term value of AQB
Recrystallized HA becoming involved in bone regeneration to a downgraded bone
Tsutsumi: The idea of implants at the time of AQB launch were all two-piece, two-stage type, and the
body was all made of titanium alone, so it was indeed difficult times for it to be successful.
With the release of an academic article in the U.S. criticizing the gradual solubility of HA over time, thegeneral views in Japan became anti-HA.
Although crystallinity and crystal structures of AQB recrystallized HA are distinct from other HA,
without long-term evidence it was difficult to prove its excellent properties. I‟m sure the professors in thisroom pointed this out.
The long-term applications of AQB for over ten years have been presented in this book by the four
professors who joined me in the AQB discussion today. I would like each of your views on the long-term
outcome of AQB treatment.
Miyazawa: The five cases, all of which have been over ten years since the beginning of their treatments
have all shown satisfactory outcome. It is true that at the time when AQB was first launched, there wereconcerns as to risks of infection, especially because of its one-piece structure, and the skeptical views on
the use of HA. The argument that the use of one-piece type is at higher risk of infection than the two-piecetype is irrelevant, and in addition, the AQB coating is not just HA that had been applied in the past, but isa recrystallized form that is extremely pure. But the actual clinical results, based on the excellent
properties, showed that the primary integration with the bone to be achieved in six to nine months, andthe placement of the superstructure to be possible in two months. This concrete evidence helped theclinicians, applying this product, to recognize its clinical efficacy.
Kuroyama: The three cases of AQB one-piece and two-piece type, all have been clinically applied within ashort period of time since its release. The typical concern with the long-term clinical examples is the issueof bone resorption occurring at the bone ridge. However, the cases that were presented showed nosignificant signs of bone resorption for the period of over 14 years. This is thought to indicate the firminteraction between the bone and HA coating layer to be effective in inhibiting the epithelial downgrowth.
The seven year study of two-piece type has not shown any signs of loosening of the screw that is holding
the fixture and abutment together, and stability in superstructure is evident. The SOL interdigitation
system is thought to be contributing to this fact.

Fig 3. “SOL system” original interdigitation form of AQB two-piece type

Tsuyama: The long-term clinical examples that began from the start of the clinical trials in Mitsui
Memorial Hospital in 1988 have been followed over the years. The four case studies that were presented
in the book are all cases that have been observed for over 17 years. The long-term clinical examples of theprofessors do not show major bone resorption, and show downgrowth to even recover slightly. Further, thebone surrounding the implant shows more opaqueness than the beginning of the treatment. This can besaid to be the property of AQB implants. The excellent properties of AQB in long-term is evident from the191/2-year study of free-end denture with three implants to the mandible (Fig. 4), conducted by Dr
Kinubuchi, the longest case study in the history of AQB.

Fig. 4 Dental radiographic appearance of implant: Two weeks after the surgery (Left) and 191/2 years after
the surgery (Right). No signs of bone resorption was observed even after 19 years. (Picture was presented
by Dr. Takao Kinebuchi, Kinebuchi Dental Clinic and Dr. Yasuhiko Tsuyama, Mitsui Memorial Hospital).
Kinubuchi: I agree that recovery of downgrowth does indeed occur as mentioned by Dr Tsuyama. It is
unthought-of with general titanium implants. In the book, I described the modification of the bone withtime. With biointegrating implant such as AQB, I felt as if the implant structure itself was forming
necessary amounts of bone where it was required as an integrated part of the bone. This is purely my own
opinion, but were derived from the actual observation and finding similar processes.
Tsutsumi: Dr Kunubuchi has also provided us with the statistical analysis of the cases (Table 2). The
97.3% survival rate after the superstructure placement is incredible.

Kunubuchi: The AQB implant cases of approximately 1500 that I conducted from the time at Mitsui
Memorial Hospital up to now have been included in this analysis. There have been 49 failure cases thatconsist of implants that were removed as a result of infection at the initial stages, therefore giving
survival rate of 96.7% with a simple calculation. In the 49 cases, there were examples where the bones
were thin to the extent that the implanting even with the socket-lift technique were difficult; or where thegreat degree of indentation on the buccal side of the bone had resulted in bone fissure, and the HA coating
layer had become exposed, to which thin bone fragment was used to facilitate the implantation. The
majority of the cases were challenging as demonstrated by the following example: a case whereby thelooseness of the implant would not disappear even a month after the implantation. This would normallybe considered for re-implantation, but the fusion with the bone was achieved with temporary fixture. The
survival rate of 97%, considering the most of the failure cases involved complex procedures, is quite agood number. This figure would be even higher in examples with favorable conditions including stablebone structures.
Tsutsumi: Also from my experience, there are several cases starting from the clinical trials that have been
observed with favorable outcome, for over 20 years after the operation.
There have been over 500,000 AQB implants installed in Japan, with the application of internationallypatented recrystallized HA coating technology. As mentioned in Part 7 - „Statistical analysis of the clinicalimplanted state and implant cases with various AQB Implant types and the model‟, by taking few key
points into consideration, satisfactory outcome from the actual surgery should be possible.

For safe and secure operation with AQB
Selecting one-piece, T-type and two-piece types

Reduce the risk ofperiodontal disease
Hydrothermal treatment(Treatment to improvebiocompatibility)
PatentExcel in compatibility withthe gingiva and high sealingability for good prognosis.

Increased stability
Spiral cylinder
It has a screw structure, but does
not have drilling ability on thebone. The rotating action of theimplant can act as the driving
force needed for insertion.

Quick bonding
enables treatment
period to be
Patentshortened
Recrystallized HA coatingWith good steoconductivity,
there have been a numberof studies that have eported
integration of the bone tobe achieved within a month.

Increased range ofcases suitable for
implant treatment
The implantation procedure issimple, therefore can beeffectively applied to even the
more complex cases.

Fig. 5 The main properties of AQB one-piece implant
Tsutsumi: The major characteristic of AQB Implant is the fact that one-piece type is the mainstream
product (Fig.5). The statistics show that 85% of the current practices have been using one-piece type. I
would like to ask the professors of their views from practices regarding the case suitability of the
one-piece type, and its limits of indication; as well as the criteria for choosing T-type and two-piece type.
Kinebuchi: The AQB Implant development has been conducted fundamentally with the one-piece
one-stage type, and as I have mentioned in the chapter of „Treatment plan‟, I consider that one-piece typecan be utilized in most of the cases. The advantages of AQB one-piece implants are that it consists of 6mm root fixtures with 3 mm diameter, that are not in other implant systems, in its product lineup. With
the excellent property of recrystallized HA in quick fusion with the bone, the thickness helps to increase
the interacting surface area therefore enabling it to be applied to the cases where the vertical height of
the alveolar bone is insufficient. The operation to the alveolar bone with lack of horizontal bone quantity
can be performed with the application of 3 mm diameter implant. The major advantage of AQB is thelarge variety in size, allowing implant body with suitable length and width to be inserted into the bone
structure of various dimensions.
Kuroyama: I have personally experienced that the one-piece type can be applied to those cases where
two-piece two-stage type have been recommended, such as to the GBR technique or immediate loading.
However, in situations where bone augmentation is required and the risk of contracting infection at theinitial stages, the application of two-piece two-stage type may be more suitable, and reduce the infection
risk. As I touched on the subject in Part 2, Chapter 4 „Treatment plan‟ of this book, I consider one-piece
implant as the first-line choice; the two-piece type where parallel insertion, and angle adjustments are
required; and T-type where there is a risk of subsidence into the bone or require strength, in order toachieve good clinical progress.
Miyazawa: I don‟t agree with the notion that two-piece type to have higher degree of freedom, in terms of
prosthetic restoration. The crown arises from the tooth cervix in both one-piece and two-piece types, andthere is no distinct difference between these. The issue of hygiene is often brought up as the problem of

the one-piece type, but in my experience of implanting two-piece type to the right and one-piece type tothe left of a edentulous maxilla (Fig. 6), the state of oral hygiene has continuously been significantly
better with the one-piece type.

Fig. 6 A case in which two-piece type was installed to the right and one-piece type to the left side of theedentulous maxilla.
Intraoral image (left) and panoramic radiographic appearance (right) taken roughly three years after
surgery. Superstructures are all hybrid crowns; gingival inflammation on the left side to which one-piece
implant installed was only slight, but shows exposure of HA coating on the cervical region. Exposure of
HA coating on the cervical region on right side to which two-piece was installed was not observed, butshowed gingival inflammation.
Tsuyama: The current implant treatment expected by both the patients and the practitioners are with thefour following points: ① safe and secure operation, ②long-term stability, ③ shortening of the timerequired for the overall treatment, with immediate loading, ④ reducing the degree of surgical invasion.
The shortening of the treatment period has been considered by most of the present implant systems.
There is no doubt that the use of one-piece type is advantageous to meet all of these four requirements. I
have been investigating the limits of one-piece one-stage type to clarify the potential application of
one-piece type in those clinical examples where the one-piece type had not been recommended such as tothe bone that has less than 5 mm in vertical bone quantity. With the introduction of T-type, the range that
one-piece one-stage type can be applied to have increased even further. Even the implantation to themaxillary molars with less than 3 mm bone width in which primary stability could not be establishedpreviously, can now be achieved with the application of T-type.
Tsutsumi: The T-type, from my experience, has shown possibility of its application to the maxillary
molars that have particularly soft bone structures. It has been two years since T-type was first introduced,
so the long-term observation of the case will need to ve conducted.
There are one-piece, T-type, and two-piece types a wide variety to choose from within AQB (Fig. 7), thus
requiring accurate diagnosis and suitable procedures to be conducted accordingly with the findings to
maximize the excellent properties of AQB.

One –piece type• Simple surgicalprocedures and simple
form

One –piece T typeTwo–piece type

•Increased range of cases to •To enable esthetic
apply implant treatment
restoration

The diameter of the abutment The
wide
range
of
is 0.4 mm wider than the one- abutments allows esthetic
piece type that was initially recovery with the crowndeveloped. This can give added structure. The inclination ofstability if applied to the the anterior teeth can becomplex cases in which the achieved.
vertical height of the alveolar •Good compatibility
bone is insufficient for usually with overdenture
type.
•Strengthened structure by one-piece
By the development of•Increased
strength for
its unified structure
various
overdenture
the lateral force
The seamless form of one- The strengthening to the abutment, a wide range ofpiece
implant
increases lateral forces has been done overdenture types can bestrength, and there is no risk of with the unique threading applied, including magnet,
screw loosening.
O-ring, and bar dentures.
technique to the screws.
Spiral cylinder type artificial
tooth root that is one-piece
one-stage type. The one timesurgery is effective in reducing
the amount of stress felt by
the patient.

Fig. 7 Lineup of AQB implant products
For safe and secure operation with AQB
What is the safe and secure surgical procedure facilitated by the bone augmentation?
Tsutsumi: Now, I would like to discuss the factors necessary in operation to achieve favorable long-term
outcome. In particular, bone augmentation procedure has become one of the most invaluable techniquesin current implant treatment. Tell us with how you have applied this technique to the clinical practiceand the advice as to how to achieve good outcome.
Kinebuchi: I consider the basic technique is to open the flap, to place a suitable size implant to the areawith favorable conditions with one-piece type, a concept which is fundamentally different to the methodwith which the two-piece type is inserted to a position where there is lack in bone quantity, facilitated by
the bone augmentation procedure with top-down treatment. However, to the positions such as theanterior region of the maxilla where esthetics is required, bone extracted from the maxillary tuberosity or
the mandibular mental region is used to graft to the deficient part of the bone. In the mandibular region
where the vertical bone quantity is lacking, socket-lift technique that uses spiral drill to pierce throughthe bone is employed (Part 6, Chapter 3- „Socket-lift method with drilling through the bone‟). Sinus-lift
procedure is a relatively advanced technique that requires surgical training, therefore should not be
considered lightly for its application.
Tsutsumi: Do you use bone filling material with socket-lift procedure?
Kinebuchi: By elevating the schneiderian membrane, the created space becomes filled with platelets so I
have not used bone filling agents. The bone is regenerated even with titanium implants, but I haveexperienced the rapid regeneration of the bone with recrystallized HA coating.
Miyazawa: I also practice with placing the importance of maximizing the use of the residing bone.
Implantation is desired to be conducted with full consideration as to the vertical bone resorption that
occurs over the years. The importance lies in taking multiple factors into account including specificproperties of implants: such that implant is only displaced a distance of 5 μm longitudinally, comparedto 30 μm with natural teeth; or that it is weak in the longitudinal direction; and the strength of alveolarbone in order to derive and achieve suitable occlusal pressure. This is probably the best preventative
measure against postoperative infection, overload and bone resorption from arising. To conduct safe andsecure bone augmentation procedures I consider socket-lift (Part 6, Chapter 3 „A case where a trephine
bur was used for maxillary sinus elevation‟) to be clinically effective with the use of trephine bur to lift thebone to the maxillary sinus.
Kuroyama: Indeed, the bones augmented with techniques such as GBR are required to be conducted withhaving considered the probability of bone resorption with time. I also feel that technology to synthesize
artificial bone that is highly effective needs to be developed that can replace the autogenous bone graft,particularly to ease the damages caused to the region of in which large amounts of bone has been
extracted. β-TCP has shown high clinical efficacy as a bone filling agent, but I am contemplating theapplication of α-TCP that have been found to enable large regeneration of bone, in the clinical practicein the future. As a reference, I have included the experimental data of the application of samples oftitanium plasma coated with α-TCP to the femur of dog, during my time at graduate school (Fig. 8). The
soft X-ray radiograph of the bone filled withα-TCP, at 12 and 48 weeks, shows significant bone
generation compared to that of the control in which HA was inserted.
There has been recent rise in immediate loading technique, as mentioned by Dr Tsuyama: The pros of thistechnique are: 1. Shorten the treatment period, 2. Effective to be applied to the area where bone on the
buccal side has been resorbed, and may be subjected to further resorption with the extraction. Comparedto implanting after the healing of the extraction cavity, there is added concern of the bone and gingivae in
the neck region of the implant to thin down with time. It might be an idea to secure the thickness byplacing fixed gingivae to the implant surroundings.

Fig. 8 Soft X-ray appearance of - TCP and HA coating sample(Source: Yushiro Kuroyama, Characterization and bone tissue rejection of - TCP plasma coated titaniummaterial, J. J. Dent. Mater., Vol. 12, No. 6, 773-789, 1993)
Tsuyama: Horizontal bone width of more than 1 mm surrounding the implant is desired. Therefore for an
implant of 4 mm diameter, a horizontal bone width of over 6 mm becomes an essential requirement. With
regards to the vertical bone quantity, to enable full insertion of the HA coating layer, a length of plus 2
mm vertical bone quantity is required. For a single insertion, implants of over 8 mm length arerecommended therefore a vertical height of 10 mm is the minimum requirement. Therefore a condition
that qualifies these criteria becomes the initial check point, and the bone augmentation procedures havebeen employed in situations where these were not met. The best method in which to conduct bone

augmentation procedure, in terms of reducing the risk of infection and shortening of the treatment period,
would be to implant with autogenous bone that have adopted the property of osteoindiction from AQB
recrystallized HA. There have been cases where sinus-lift techniques done, with only using autogenous
bone, have resulted in favorable outcome. I will present the efficacy of this technique with the resultsfrom the long-term clinical examples in the future.
Tsutsumi: Lastly, I would like each of you to give us one last advice.
Tsuyama: To conduct safe and secure procedure, the complete insertion of the implant to cover the HA
coating with the bone, and complying to this basic rule is fundamental to the success of implant
treatment
Kinebuchi: I agree. Also, implant treatment is one that combines all the procedures of oral andmaxillofacial surgery. The techniques of incision, detachment, milling, suture, postoperative care andobservation is cultivated by the everyday practice of horizontal wisdom tooth extraction and gingival flap
operation, therefore it is important not to neglect the general oral surgical practice.
Kuroyama: The success rate of implant treatment has not yet reached 100%, and unfortunately there areexamples in which they have to be extracted. Investigating the reasons and the underlined mechanisms
scientifically, I believe, is the task that has to be conducted for the future development of implant.
Miyazawa: The determining factors for the prognosis of the implant treatment with regartds to the AQB,
I think, is beyond the innate properties of AQB, it all comes down to the mechanical force, occlusal force
that is exerted on the implant body via the superstructure, and the extent that the surrounding alveolarbone can withstand this. The superstructures of implants with that of the natural teeth are essentially
distinct therefore implementation of 3D stress analysis to derive at an unique occlusal theory may berequired in the future.
Tsutsumi: There is no doubt that the practice of implanting technique conducted true to the basics;
gradually expanding the scope of its application; and the development of prosthesis that has implemented
occlusion unique to the implant will contribute greatly to the improvement in the prognosis of implant
treatment.
I hope safe and secure surgery will be conducted in a way to maximize the properties of AQB will be
continued.